a) Field of the Invention
The invention relates to a miniature fan which is mounted on a printed circuit board and circulates air to help dissipate heat in enclosed electronic packages. The structure of the invention allows the miniature fan to be mounted in a method which simplifies the mounting process of the fan onto the circuit board such that mounting screws or hand soldering of lead wires are eliminated, thus increasing efficiency and reducing cost.
b) Description of Related Art
Most electronic devices, such as used in electronic circuits, have high performance characteristics, and are low in mass and volume which results in high circuit density. During operation great amounts of heat are developed inside the enclosed device which must be dissipated and removed from the enclosed device to avoid failure due to heat build-up. The device cannot store this heat, and so the heat must be dissipated. One method is the use of heat sinks which are mounted in contact with heat generating electronic parts. The heat sinks transfer the developed heat to a greater area. But this is not sufficient in most instances, and so the further removal of heat is brought about by forced cooling air. Generally, such forced air is accomplished by fans mounted within the electronic device. These fans are typically mounted on the circuit enclosures device housing by means of screws or bolts which require a separate circuit assembly step.
For instance, U.S. Pat. No. 5,191,230 to Heung discloses a circuit module fan assembly wherein multiple modular circuit boards are mounted in parallel within a circuit housing. A modular fan assembly board is mounted in parallel with these modular circuit boards in order to dissipate heat therefrom. The assembly of Heung requires a separate circuit board for the modular fan assembly which is bolted thereto.
U.S. Pat. No. 4,885,488 to Cox discloses a miniature fan mounted on a printed circuit board. However, the assembly of Cox comprises a permanent magnet disposed on a first side of the circuit board and electromagnets on the opposite side about a bearing member; threaded members rotatably secure the fan blade to the bearing member. The assembly of Cox requires a plurality of screws or bolts to mount the assembly to the circuit board, and is disposed on both side of the circuit board.
U.S. Pat. No. 4,513,812 to Papst et al. discloses a heat sink fan mounted directly on a heat sink plate with cooling ribs. The fan is disposed in a manner to provide efficient forced air cooling between the heat sink cooling ribs, however, is not suitable for assembly directly on a printed circuit board and requires mounting cooling ribs or vanes.
Electric devices i.e. transistors, capacitors, resistors, mounted on the PC boards are typically provided with mounting pins which pass through the PC board and are subjected to a wave soldering process whereby these components are soldered in place in an assembly-line fashion. The prior art cooling fans are mounted on the housing or PC board by screws and bolts, thus cannot be incorporated into the electric device assembly process, and require an additional assembly step.